Fair Value Measurements And Disclosure (Notional Amount Of Our Outstanding Derivative Positions) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Derivative [Line Items]
Notional Amount of Outstanding Derivative Positions	$ 51,911	$ 48,527
Interest Rate Swaps [Member]
Derivative [Line Items]
Notional Amount of Outstanding Derivative Positions	7,333	9,833
Cross-Currency Swaps [Member]
Derivative [Line Items]
Notional Amount of Outstanding Derivative Positions	42,192	38,694
Foreign Exchange Contracts [Member]
Derivative [Line Items]
Notional Amount of Outstanding Derivative Positions	$ 2,386	$ 0